Orchids of New Guinea

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Corybas helensis

Corybas helensis S.P.Lyon, Malesian Orchid J. 18 (2016) 98, fig. 16-18.

Type: .P. Lyon SPL 459 (holo LAE, iso L).

Terrestrial herb. Tuberoid ovoid, 1.3 by 1 cm. Stem slightly angular, 1.2 cm long; basal sheath 0.6 cm, with acute apex. Leaf sessile, ovate to elliptic, 2–4 by 2 cm, glabrous; margins slightly undulate and revolute; apex apiculate; nerves reticulate, two nerves on either side of the midrib, the outermost extending most of the way to the apex. Peduncle purplish, c. 0.1 cm long. Floral bract narrowly triangular, clasping the base of the ovary, 1.05 cm long; keeled; apex subulate. Ovary 0.45 cm long, ribbed. Flower solitary, upright. Median sepal spathulate-obovate with broad base, 2.9 by 0.9 cm; apex broadly rounded, hooded over lip; on the outside with c. 13 strongly crested nerves, becoming irregularly ridged towards the apex. Lateral sepals falcate, c. 0.75 cm long, emerging from behind spurs. Petals falcate, 0.3 cm long. Lip ventral part of the tube from the tubular basal part inflated and laterally compressed, abruptly curved downward and spreading into the 0.8 cm wide expanded blade, 1.7 cm long when flattened; inner surface of blade densely hispid; margins shortly fimbriate; opening to the floral tube rounded, without a boss; spurs narrowly conical, c. 0.2 cm long. Column upright, 0.3 by 0.2 cm; anther narrower; ventral pad 0.1 by 0.2 cm. Fruit not seen.
(after Lyon 2016).

Colours:

Leaf greyish green with pale nerves and broad whitish midrib above, suffused purple between nerves below. Floral bract purplish. Pedicel and ovary green with irregular purple streaks. Median sepal on outer surface pure white, inner surface with a dark purple patch inside the hood towards the apex. Lateral sepals and petals whitish. Outer surface of lip tube white with purple on ventral inflated part; spurs white; inner surface of lip blade strongly marked purple, with numerous fine purple longitudinal streaks merging towards the solid purple margin and becoming narrower laterally; pale “window” at the back of the lip tube visible through the opening in the blade.

Habitat:

Terrestrial in thick moss in montane forest. Altitude c. 2600–3150 m.

Distribution:

Malesia (New Guinea, endemic).

Distribution New Guinea:

Papua New Guinea (Enga, Hela and Westren Highlands Prov.). See map

Cultivation:

Cool growing terrestrial.

Flowering time in the wild:

January.

Classification:

Family Orchidaceae
Subfamily Orchidoideae
Tribe Diurideae
Subtribe Acianthinae
Genus Corybas
Species Corybas Corybas helensis

Notes:

Corybas helensis is similar to C. aduncus but differs in the less distended and laterally compressed ventral part of the lip tube, the more expanded blade with a fimbriate margin (versus entire), the densely hispid surface (versus covered in irregular warts), and the pure white outside of themedian sepal (versus dotted pink), with strongly crested nerves (versus small irregular warts).